Retardation of rancidity



Patented Apr. 6, 1931 Albert K. Epstein and Beats mileage,

masses nnmnnn'non on No Drawing. Application June 3, 1935, Se

. No. H.711

16 Claims.

Our invention relates to methods of and means .for retarding or preventing spoilage or decomposition of materials having an oily constituent subiect to oxidation. .Theinvention concerns itself with improved products having the property of resisting decomposition caused by oxidation and of imparting resistance to spoilage caused by oxi-.

dation.

It is known that many types of materials, such as oils and fats and materials in which oils and fats are a constituent, are adversely afiected by' the presence of oxygen in the air, in that decomposition, presumed to be caused directly by oxidation, takes place and, in general, renders-the article unfit for its intended use. This decomposition or spoilage sometimes manifests itself asrancidity, sometimes by discoloration, and sometimes by the loss or destruction of some important constituent, .as, for example, the vitamin A constituent of cod liver oil.

Although considerable work has been done lcokingtoward the development of anti-catalysts or antioxidants in oils, fats and the like normally subject to oxidation, theart has not developed sumciently to enable one to predict what substances, or even whattypes or substances, will have a retarding or .inhibiting-eifect'. It is known, however, that certain substances which have some anti-oxidant effect in oils and fats normally sub ject to oxidation, will notfunotion in the presence of other substances, as for example relatively heavy metals such as copper, iron and co'- balt. These metals, as well as other substances,

are said to poison" the anti-catalyst or antioxidant. Ithas been found, also, that if in a given chemical substance which acts as'an antioxidant or anticatalyst, a new chemical group or radical be introduced, or the position or character of groups present in the-antioxidant molecule be changed, then the-potency of the chemical substance as an antioxidant or anticatalyst is decreased-or entirely destroyed. r I

.Accordingly; the principal object of our invention is the provision of an improved class of anti;

. oxidants' of an edible innocuous nature.

Another object is to retard orjprevent the 0111-:

dation of organic substances, particularly oils and fats, and substances having oils and fats as con- 'stituents thereof. I e

Other objects and features of the invention are apparent from the foregoing description of problems involved and the following description of the manner in which these. problems are overcome.

. prising g1yco1s,polyg1ycols and polyglycerols, with at least one free hydroxy group attached to a carbon of the polyhvdroxy substance, with a derivative of phosphorus capable of producing ,an ester of a phosphoric acid, \have a definite anti- 10 oxidant or anticatalytic efiect,'particular1y in oils and fats and compositions having an oily or fatty constituent. The organic carboxylic acid radical, preferably a fatty acid radical, maybe of relatively low, intermediate, or relatively high molecular weight, the latter offering certain advantages in many instances. Preferably the fatty acid radical should have at least eight carbon atoms. Certain of the esters of phosphoric acids seem, in general, to be more potent than others, as will be pointed out. Simple phosphoric acid esters of glycols, polyglycols and polylllycerols may also be used. Such estersoi phosphoric acids may be treated with alkaline substances to form acid or other salts, or may be left untreated, as desired. w The preferred type of phosphoric acid ester used in accordance with our invention is that wherein polyhydroxy substances, such as glycols,

polyglycerols or polyglycols, esterined with a rel-.

atively high molecular weight fatty acid haveat least one remaining hydroxy group esterifled with a phosphoric acid. In general, reaction products comprising mixtures have certainadvantages-over relativelypure substances. Mixtures containing a relatively large proportion ofglyceride estersmay also be employed as.will be explained further hereinafter.

In general, the substances described inthe copending application of Harris, Serial No. 705,825,

now Patent No. 2,026,785, are all suitable for use as antioxidants, as well as the reaction products described in the oopendingapplication Serial No.

14,528, filed April 3, 1935, as acontinuation in part thereof and which is now Patent No. 5 7

2,025,986. While the composition of the phosphate. substances employed inthe present invention may vary, the substances should in themresidue of a glycol, polyglycol or polyglycerol. 5s

Example A To 75 parts of washed and dried coconut oil mono-fatty acid esters of diethylene glycol are added, with stirring, 15 parts of phosphorus pentoxide, at about room temperature, or slight- 1y above. The temperature rises to about 70 C.,

and the reaction mixture is held at this temper- Example B parts of mono-stearyl diethylene glycol prepared from commercial stearic acid and dieth- 'ylene glycol by esterifying the commercial stearic acid with an excess of diethylene glycol, are dis- 'solved in 250 parts of dry pyridine, and are added to 44 parts of phosphorus oxychloride dissolved in 250 parts of dry acetone in a cold condition. The solutions are suitably mixed and allowed to 0 stand over night or until reaction has gone to completion. The acetone is then evaporated, the product dispersed in cold water, and then salted out employing on the average approximately 18% of salt. The salted-out product is boiled with about 150 cc. of water and then evaporated to dryness. The product so prepared may be treated further with an alkaline agent or it may be employed in the acidcondition.

Example C Substantially water-free glycerine is polymerized, preferably with the aid of-an alkali catalyst, until it has an average molecular weight corresponding to a diglycerol. 166 parts of the poly- 5 merized product, 180 parts of oleic acid, and 105 parts of stearic acid of good commercial grade are mixed together and heated to a temperature of about 220 to 225 C. and maintained at that temperature for approximately two hours, the

0 reaction mixture in the meantime being continuously stirred. Atmospheric oxygen is kept out ofcontact with the mixture, preferably by maintaining an atmosphere of an inert gas at the surface, for example, by bubbling carbon dioxide through the mixture continuously. The reaction should be allowed to continue until the acidity of the mixture is below'1%, the time, temperature and conditions described usually being suitable to produce this result. The product is then allowed to stand and any unreacted polyglycerol present is allowed to settle out.

To 450 parts of the mixed polyglycerol esters prepared as in the preceding paragraph, while at a temperature of approximately 60 C., 75 to parts of finelydivided phosphorus pentoxide are slowly added. A jacketed vessel may be employed to control temperature. The product is heated to approximately C. and kept at that temperature for about twenty minutes; It is then removed from the vessel and centrifuged to remove insoluble materials, consisting for the most part of more or less altered phosphorus pentoxide and adhering or loosely combined organic matter. I

400 parts of this pretreated product are returned to the jacketed vessel and at 50 C. fifty parts of finely divided phosphorus-pentoxide are added slowly thereto with vigorous stirring. The reaction mixture is heated to about 70 C. and the temperature then rises to about 95 C. The product is kept at this temperature for a few minutes, the total time for the entire esteriflcation step being about twenty-five minutes.

The product so prepared may be used as such or it may be treated with an anti-acid material such as sodium carbonate or ammonia to improve, somewhat', its keeping qualities.

The above examples illustrate generally suitable method's employable for producing the products which we utilize in our'in'vention. It is to be understood that many modifications can be made not only in the processes but in the substances as well. For example, in producing the polyglyceride substances, the polyglycerol may have various average molecular weights by carrying out the polymerization so that the average of molecular weight will'be' greater or even lower than a diglycerol. In the copending application of Harris, Serial No. 754,087, filed November 21, 1934, various methods of making the polyglycerol and fatty acid esters thereof are described. Substantially any fatty acid esters of polyglycerol with at least one unesterified hydroxy group can be treated to form the ester of a phosphoric acid and the resulting reaction product can be utilized in our invention.- I

greater amount ofcombined phosphorus in the reaction product as a whole.

In place of esterifying polyglycerol with fatty acids, we may re-esterify oils and fats with the polyglycerol, in which case a mixture of monoand diglycerides together with polyglycerides will be present and this entire mixture may be treated to forin the ester. The product so produced can Example D 25 parts of the mono-acid esters of mixed coconut fatty acids and ethylene glycol are treated with 54 ,parts of pyro-phos'phoric acid.

The pyro-phosphori'c acid is added when the Commercial ste'aric acid is esteri iled with an aomeoe excess of polglycerols having the average molecular weight oi! a tetra glycerol to produce an esterifled product consisting essentially of the mono-stearyl tetra-glycerol. 73 parts of this esterifled product are treated with 54 parts of pyro-phosphoric. acid, the mixturebeing made at a temperature not greater than about 90 C. and the product allowed to stand for about twenty minutes or until there is no further rise in tem- '10 perature. The temperature ofthe mixture rises to apl giroximately 125- C. and the reaction mix-' ture then allowed to cool;

The organic carboxylic acids employed in our invention to esterify the polyhydroxy substances is preparatory to the treatment to form the phosphoric acid esters are preferably fatty acids of relatively high molecular weight, say from Ca up. We may employ saturated fatty acids or we may employ unsaturated fatty acids which in themselves are subject to oxidation. Substantially any of the fatty acids derived from-the oils and fats of commerce may be employed, such as vegetable oils, for example, cotton seed oil. corn oil, castor oil, peanut oil, and the like, fish oils, such as sardine oil, or animal fats such as lard. While,

preferably, in accordance with the present invention, the free fatty acids prepared by suitable means' from the oils or fats are preferred, we may also in many instances re-esterify the oil or fat directly with a suitable polyhydroxy substance such as polyglycerol to produce a'mixture oi. fatty acid esters ,having' free hydroxy groups capable 0! being esterifled to form esters ofa phosphoric acid.

.35 In the treatment of the reaction product consodium carbonate, in amounts in excess of that theoretically necessary to completely neutralize 5 the product. That portion oi! the neutralizing .agent which has not reacted is then removed by filter pressing, centrifuging or the like. The acid salts are very potent as anti-oxidants or anticatalysts, and the ammonium salts, in general, produce better results than alkali metal salts such as sodium salts.

Our products may be made in various ways, and

any derivative of phosphorus may be used, capable of forming an ester of phosphoric acid. Examples of such phosphorus containing substances are phosphorus pentoxid'e pyrophosphoric acid, phosphorus halides, meta-phosphates such as ethyl meta-phosphate, phosphorus oxychlorides, 'etc.

In preparing simple .esters of the polyhydroxy substancesof the class described. the esteriiication procedure described above in general may be employed. Forexample, 6.7 parts of ethylene glycol are treated with 54 parts of pyrophosphoric acid at approximately ,room temperature. ,I'he

temperature of the reaction product rises to about 55 to 60 (2., and the product is then heated to about 90 C. for about twenty minutes. When =,treating-diethyleneglycol or-a p'olyglycerol prod- 'uct consisting essentially otdiglycerol, amounts A suitable suitably used are 11.4 and 19.3 parts, respectively, to 54 parts of pyrophosphoric acid. The spontaneous rise-in temperature in each case is somewhat greater than in the case of the ethylene glycol, but the heating step may be about the same.

After esteriflcation, the products are purified by filtering, decanting, or the like, to remove unreacted pyrophosphoric acid.- The phosphoric acid esters may be used as such, or may, if desired,

be neutralized, at least in part, with a-suitable anti-acid substance.

Example F Pure, fresh cod liver oil is treated by the addition of approximately ,5 to 35% of the reaction product of'Example C. So treated, the cod liver oil will-keep for a very much longer period of time than cod liver oil not so treated. Furthermore, the vitamin A content of the cod liver oil will remain unaflected after comparatively long periods of storage. Even if the oil is contaminated with known oxidation catalysts, such as copper, iron, nickel and other common metal contami ts, the anti-oxidants exert their action and retard'oxidation. The amount of antioxidant substance used in any particular produgt -may vary. Generally, amounts as low as .0 maybe used with satisfaction, but considerably greater amounts may be employed in most cases with good results.

The particular phosphoric acid esters employed in accordance with our present invention are innocuous even it present in relatively high concentrations. This enables us to employ such phos-, phoric acid esters as oxidation inhibitors in substantially any types of organic substances which in themselvaare employed ,as food, or which areemployed'as ingredients of foods. When employed in proportions of one-half percent or less and up to,10% based upon the oleaginous constituent oi the product treated, remarkable and valuable properties. are imparted to many types longer periods of time without suflering the type of deterioration usually accompanying oxidation.

Our improved antioxidants have an advantage in' being, in general, readily soluble in or miscible with oily or fatty substances. Stock solutions or mixtures are, therefore, readily made up and easily handled containing a reiatively large proportion or the antioxidant, for example, 30% to 40%.

Among the classesof substances-which can be treated very satisfactorily in accordance with our present invention are substantially all of the oils and fats of commerce, such as cod liver oil, hallbut liver oil, sardine oil, salmon oil and other fish oils, cotton seed oil, peanut oil, sesame oil, rape seed oil, lard, vegetable shortenings, and other animal and vegetable oils and fats. Many of these oils and fats are employed'aione. while some of them are also employed in various ways in the food and other industries, as for example, in the -form' of emulsions in which they are in contact with moisture, which is known to cause oxidation to occur much morereadily'gwhile atother times ,these materials are mixed orassociated with.

farinaceous or vegetable substances. Examples of such substances are the residues oi oil extraction from seeds, or animal fat renderings eni- .0! materials, enabling them to be kept for much v ployed as cattle food and for other purposes, nuts. which areoften coated ortreated with oils, be-

sides having an oil content oftheir own, dried 4 15 ao'raaoe milk powders, baked flour products oiall kinds such as certain types of biscuits, crackers, and the like, which are kept for comparatively long periods of time, potato chips, and the like. Flour preparations of various kinds, such as biscuit or cake flours, containing proteins as in milk powder, a shortening ingredient, etc., can be protected by the use of our antioxidant substances. In all materials of the character named, spoilage of a type promoted by oxidation is definitely retarded by the use of phosphoric acid esters of the type described, and in some cases substantially complete inhibition for comparatively long periods is effected.

When treating such substances as dried milk powder, for example, the antioxidant initially may be dispersed in the liquid milk, and the milk then dried in'a suitable manner, for example, by spray-drying. This procedure not only results in an intimate dispersion of the antioxidant, but

the antioxidant protects the oxidlzable constituents of the milk duringthe drying process.

Example G Fresh, pure lard is treated by the addition thereto of one-half percent. of the product of Example B. The reaction product of Example B may be used in its acid condition or in a partially neutraliaed condition with good results. In treating the lard, it is advisable that a thorough dispersion be obtained, and this is readily done by first mixing the ester with a portion ofthe lard and then incorporating this mixture into the balance of the lard. The preferred method, however, is

to incorporate the ester while the lard is in a melted condition, employing suitable agitation, and then spreading the treated lard out on a socalled lard roll from which it is scraped in the customary way. The lard so treated can be stored for much longer periods of time and with less precautions against spoilage than lard not so treated.

. Example H ester prepared as described in Example A are added with agitation and in a suitable manner to prepare a thoroughly homogeneous mixture. This product will keep for long periods of time, 'the ester being of oleaginous character will not readily separate out, or if there should be any slight separation, simple mixing will restore homogeneity. The product may be used as such, but preferably is adapted i or treating other substances having an oleaginous constituent normally subject to oxidation. This ailords a suitable vehicle for the treatment of substances with relatively small amounts of an antioxidant.

What we claim as new and desire to protect by 00 Letters Patent of the United States is:

l. The method of retarding oxidation of organic materials having an oleaginous constituent normally subject to oxidation, which comprises incorporating into such materials an unneutralized 65 or partially neutralized phosphoric acid ester of a polyhydroxy substance of the class consisting of To parts of cottonseed oil, 40 parts of the.

a polyhydroxy substance of the class consisting of glycols, polyglycols and polyglycerols, wherein at least one hydroxy group of the polyhydrow substance is esterifled with a relatively high molecular weight aliphatic organic carboxylic acid.

3. The method of retarding oxidation of organic materials having an oleaginous constituent normally subject to oxidation, which 'comprises incorporating into such materials an unneutralized or partially neutralized phosphoric acid ester of a polyhydroxy substance of the class consisting of glycols, polyglycols and polyglycerols, wherein at least one hydroxy group of the polyhydroxy substance is replaced by a relatively high molecular weight fatty acid radical. I

4. The method defined in claim 1, wherein the ester of the polyhydroxy substance also includes a proportion of a relatively high molecular weight glyceride which in itselfhas at least one hydroxy group esterifiable with a phosphoric acid.

5. The method of retarding the oxidation of organic materials having an oleaginous constituent normally subject to oxidation which comprises introducing into saidmaterials a propor tion of an ester in the form of a reaction product of a relatively high molecular weight organic carboxylic acid ester of a polyhydroxy substance of the class consisting of glycols, polyglycols, and polyglycerols, said ester having at least one unesterifled hydroxy group, and a derivative 01' phosphorus capable of forming an ester of a phosphoric acid, said ester being unneutralized or partially neutralized.

'6. The method or retarding the oxidation oi. organic materialshaving an 'oleaginous constituent normally subject to oxidation which comprises introducing into said materials a proportion of an ester in the form of a reaction product of a relatively high molecular weight organic carboxylic acid ester of a polyhydroxy substance oi. the class consisting of glycols, polyglycols, and poly glycerols, said ester having at least one unesterified hydroxy group, and phosphorous pentoxide, said ester being unneutralized or partially ne tralized.

The method of retarding the oxidation of organic materials having an oleaginous constituent normally subject to oxidation, which comprises introducing into said materials a proportion of an unneutralized or partially neutralized ester of phosphoric acid formed by pretreating a mono-fatty acid ester of a polyhydroxy substance of the class consisting of glycols, polyglycols and polyglycerols with phosphorus pentoxide, and then reacting the resulting product with a derivative of phosphorus capable of forming an ester of a phosphoric acid.

8.:1he method of retarding the oxidation of organic materials having an oieaginous constituent,normally subject to oxidation, which comprises introducing into said materials a proportion of an unneutralized or partially neutralized ester of phosphoric acid formed by pretreating a mono-fatty acid ester of a polyhydroxy substance of the class consisting of glycols,.polyglycols and polyglycerols with phosphorus pentoxide, removing the phosphorus pentoxide material and adhering organic matter, and then reacting the resulting product witha derivative of phosphorus capable of forming an ester of a phosphoric acid.

9. The method of retarding oxidation of oils and fats in the presence of oxidation catalysts such as heavy metals, which comprises introducing into said materials a proportion of an unneutralized or partially neutralized phosphor:

acid ester of a polyhydroxy substance of the class consisting of glycols, polyglycols and polyglycerols, wherein at least one hydroxylroup oi the polyhydroxy substance is esterifled with arrelatively high molecular weight "fatty-acid; 7 10. A substantially dry product comprising oleaginous material normally'subject to oxidation, having incorporated therein a phosphoric acid ester of a polyhydroxy substance of the class 10 consisting of glycols, polyglycols and polyglycerols,- wherein at least one hydroxy group or the polyhydroxy substance is replaced by a relativelyhigh molecular weight aliphatic lipophile radical.'- NV 15 11. A substantially dry product comprising oleaginousmaterial normally subject to oxidation. having incorporated therein a phosphoric acid ester of a polyhydroxy substance or the class consisting of glycols, polyglycols and polygiycl0 erols, wherein at least one hydroxy group of the polyhydroxy substance is replaced'by a relatively ;high molecular weight fattyacid radical. L I 12. A. substantially dry product comprising oleag'inous material normally subject to oxida 25 tion, having incorporated therein a phosphoric acid ester of aipolyhydroxy substance-0L the class consisting of glycols', polyglycols and polyglycerois. v j

13. A substantially dry product comprising 80 oleaginoustmaterlal. normally subject to oxidation, having incorporated therein a phosphoric fatty acid radical.- Y

acid ester of a nolyhydroxy substance of the class consisting of glycols, polyglycols and polyglycerols, wherein at least one hydroxy group of the pblyhydroxy substance is replaced by a relatively high molecular weight aliphatic lipophile radical, said phosphoric acid ester being neutralized at least in part by an anti-acid substance.. t

14. A substantially dry product comprising a $15. .A substantially product. comprising a trislyceride normally subject to oxidation having incorporated therein a proportion 01 a phosphoric acid ester oi a polyhydroxy substance of the class consisting ot glycols, polyglycols and polyglycerols, wherein at least one hydroxy group of the polyhydroxy substance is replaced by a 16.'A substantially dry product comprising triglyceride normally subject to oxidation having. incorporated therein a proportion of a phosphoric oleaginous material oia character normally sub- Ject to oxidation and having' incorporated therein an ester in the form of a reaction product of a derivative of phosphorus capable of forming an ester of phosphoric acid and a fatty acid ester of a polyhydroxy substance of a class consisting- 4 0! glycols, polyglycols and polyglycerols.

T 'K. EPSTEIN. BENJAIHN R. HARRIS. 

